1. Field of the Invention
The present invention relates to a method for synthesizing pure carboxyethyl germanium sesquioxide, and in particular to a chemical method for synthesizing, in bulk quantities, carboxyethyl germanium sesquioxide without trace amounts of germanium dioxide or metallic germanium.
2. Background of the Invention
It is understood that certain forms of germanium confer various health benefits to humans. See, e.g., U.S. Pat. No. 4,595,882; U.S. Pat. No. 3,793,455!. Although synthetic carboxyethyl germanium sesquioxide is a well known compound, its molecular structure has been shown to be dependent on the synthetic method employed. Uses of germanium in the human diet include preventing the overproliferation of cells, stimulating the production of interferon, and inducing contrasuppressor T cells. See, e.g., F. Suzuki and R. Pollard, J. Interferon Res., 4(2) :223-33 (1984); P. Kopf-Maier, Eur. J. Clin. Pharmacol., 47:1-16 (1994); K. Ikemoto et al., Expermentia, 52:159-166 (1996)!.
In order to use germanium as a dietary supplement, the carboxyethyl germanium sesquioxide needs to be pure, that is, essentially free of unwanted and potentially toxic contaminants germanium dioxide and metallic germanium. Many known methods for synthesizing carboxyethyl germanium sesquioxide provide for the production of germanium sesquioxide contaminated with trace amounts of metallic germanium or germanium dioxide, since these are used as the starting materials.
The key intermediates common to such known synthetic routes are trichlorogermanium acrylate moieties (trichlorogermanium acryl chlorides, trichlorogermanium acrylic acids, trichlorogermanium acroleins and trichlorogermanium alkyl acrylates), and known methods of synthesizing trichlorogermanium acrylate intermediates require either oxidation of metallic germanium with hydrochloric acid, or reduction of germanium dioxide. The problem with such methods is the significant probability of generating trace amounts of unreacted starting material (metallic germanium or germanium dioxide) in the product.